US3915066A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power boost mechanism
Assignee: Bendix GmbH
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Filing: 1973-12-03
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Granted: 1975-10-28
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Expires: 1993-12-03
Abstract
Abstract A power boost mechanism for use in a braking system of an automotive vehicle, and comprising a servomotor and a servovalve. The valve housing is provided with an inlet port, an outlet port and an exhaust port. A spool valve movable in the valve housing, includes a central bore and passages to selectively communicate the inlet port and the exhaust port with a work port connected to the working chamber of the servomotor. An output piston is located in said working chamber and comprises an output plunger projecting into an enclosed chamber filled with incompressible fluid. In the control chamber also projects an operator-actuated input member in which projects said output plunger to define therewith a cavity. The cavity communicates with said control chamber through a one-way valve and by an exhaust passage closed when said input plunger is biased toward said output plunger.
Inventors
- 👤 Alfred William Thomas
- 👤 John Redvers Botterill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:32
CPC Classifications
B; B60; B60T; B60T13/00; B60T13/10; B60T13/12
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
261 words
A power boost mechanism comprising housing means defining a working chamber and a control chamber therewithin, said control chamber being filled with incompressible fluid, a valve member responsive to the fluid pressure level in said control chamber to shift from a released position venting said working chamber to communicate successively higher fluid pressure levels into said working chamber as said valve is shifted from said released position, a piston slidably mounted in said working chamber, said fluid pressure level in said control chamber varying as a function of the displacement in said control chamber of at least one input plunger and of an output plunger moving as a whole with said piston, said input plunger being operatively disposed in said control chamber to cooperate with said output plunger in case of failure of said control pressure for permitting the manual actuation of said output piston, the input plunger/output plunger effective area ratio in said control chamber being more than unity, a relief valve responsive to the differential of pressures existing in said control chamber and said working chamber and adapted to allow fluid to escape from said control chamber when said differential of pressure reaches a predetermined value, one of said plungers projecting into the other plunger to define a cavity between said plungers communicating with said control chamber, a one-way valve permitting fluid to flow from said control chamber into said cavity, an exhaust passage also communicating the cavity with the control chamber, and means for closing said exhasut passage when said input plunger is urged towards said output plunger.
Claim 2
Dependent Claim
261 words
A power boost mechanism comprising housing means defining a working chamber and a control chamber therewithin, said control chamber being filled with incompressible fluid, a valve member responsive to the fluid pressure level in said control chamber to shift from a released position venting said working chamber to communicate successively higher fluid pressure levels into said working chamber as said valve is shifted from said released position, a piston slidably mounted in said working chamber, said fluid pressure level in said control chamber varying as a function of the displacement in said control chamber of at least one input plunger and of an output plunger moving as a whole with said piston, said input plunger being operatively disposed in said control chamber to cooperate with said output plunger in case of failure of said control pressure for permitting the manual actuation of said output piston, the input plunger/output plunger effective area ratio in said control chamber being more than unity, a relief valve responsive to the differential of pressures existing in said control chamber and said working chamber and adapted to allow fluid to escape from said control chamber when said differential of pressure reaches a predetermined value, one of said plungers projecting into the other plunger to define a cavity between said plungers communicating with said control chamber, a one-way valve permitting fluid to flow from said control chamber into said cavity, an exhaust passage also communicating the cavity with the control chamber, and means for closing said exhasut passage when said input plunger is urged towards said output plunger.
Claim 3
Dependent Claim
73 words
A power boost mechanism according to Claim 1, wherein said input plunger comprises a rod portion having one end sealingly projecting into said control chamber and a head portion located in said control chamber and slidably secured to said rod portion by a connection having an axial clearance to define a portion of said exhaust passage, said head portion being provided with a bore receiving said output plunger to define therewith said cavity.
Claim 4
Dependent Claim
25 words
A power boost mechanism according to claim 2, wherein said head portion engages said housing means when the input plunger is in its rest position.
Claim 5
Dependent Claim
29 words
A power boost mechanism according to claim 1, and a refill valve permitting fluid to flow back into said control chamber during the return stroke of said input plunger.
References Cited (Backward Citations)
US3831491A
Cited
US3838629A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |